Can SCCP be an impurity in MCCP/ LCCP?
Key summary points
- No. The chemistry of these substances means that this is extremely unlikely!
- Highly regulated SCCPs have a strict composition definition under CAS;
- The detection of chains <C14 in an MCCP product does not mean that the product contains SCCPs;
- Analytical methods and differences in international definition complicate this matter further;
In a regulatory setting, notification to ECHA is a legal requirement for imported consumer products which contain >0.1% w/w SCCP, an EU substance of very high concern. Often, there are claims that SCCPs appear in products above the limit or, even more incorrectly, in European MCCP/LCCP products. SCCP and MCCP/LCCP are very different 'chemicals'!
However, it is important to distinguish between SCCP and short carbon chain components of other longer chain UVCB substances. Regulatory action on (and definition of) SCCPs is on the substance as defined by CAS No 85535-84-8/EINECS 287-476-5 which have been tested fully. This includes chain lengths from, predominantly, C10 to C13 and the concentration of longer chain chlorinated alkane products (such as medium chain chlorinated paraffin (MCCP) or long chain chlorinated paraffin (LCCP)) is always zero.
Similarly MCCPs are defined by particular CAS and EINECS Numbers (85535-85-9/287-477-0). These are described by chain lengths of, predominantly, C14 to C17. There will be some constituents of MCCPs which lie outside this range. However they are part of the substance and will have been present when the substance was tested in regulatory required assessment. For MCCPs (and MCCP products), when small amounts of chlorinated components, that are less than 14 carbon atoms long are found, they are not SCCP but rather <C14 constituents that are part of the registered MCCP product which is a UVCB substance. SCCPs and MCCPs are not blended together, nor are C13 components added to MCCPs. MCCPs are not defined as a mixture under REACH but are defined as substances.
Chlorinated molecules can potentially also be found in chlorinated alkane products produced outside the EU (i.e. in imported products). It is important to note though that, in other global regions, chlorinated alkane substances are not always categorized by carbon chain length, but by chlorination level (e.g. China). This means that CA products used in imported consumer products could in fact be composed of other carbon chain length ranges (e.g. C10-20, 52%Cl in China). As such it is not correct to assume that any <C14 chloro alkanes found in imported products are SCCPs, as defined by the above CAS and EINECS numbers.
There are tens of thousands of possible chloro alkane chains that can be potentially found in CA products. This is amplified by analytical problems. A recent study by van Mourik et al. (2015) on the relationship between chlorine content and response factors showed that it is important to calibrate the response differences between CA constituents in order to quantify them. However, this is currently not possible because available individual congener standards used for detector calibration do not match the congeners found in commercial CA products. As such, they are not suitable to allow precise quantification of individual CA components.